...there are four features of development of doctrine that I think to which I think an adequate account must do justice: (1) richness; (2) confidelity; (3) creativity; (4) entelechy. I think that inferentialist accounts, of whatever kind, and for all their good, fall short on all four points. The alternative I've sketched here -- very sketchily! -- does better, I think, although it requires a vast amount of development. And perhaps that's as it should be.
I'm sure Newman would have agreed with that, and Brandon does indeed quote Newman in support of his points. Having recently reread Newman's essay on development myself, I entirely agree that the four features Brandon cites, and expounds on, are ones that an "adequate account" of DD must include and explain. But that implies the inadequacy of "inferentialist accounts" only if all such accounts be taken as intending a complete account of what actually goes on in DD. I admit that, for my own part, I have hitherto failed to make clear that I was not offering my account as that. The sort of account I gave only yields an intellectual template, as it were. It does not tell us that the actual process of DD consists in nothing but inference, nor is it meant to tell us that. Rather, it indicates in the most general terms that would be useful what it is about actual and genuine DD that connects that process, logically and conceptually, with the pertinent sources. That is necessary but of course not sufficient for an "adequate" account of what did and must occur. The features Brandon discusses help to fill out and apply that template. Thus, the kind of ampliative inference I posit as the norm, i.e., inference to the best explanation, must and does exhibit, in the concrete, the features Brandon discusses.
I eagerly await the further work in that vein which he has promised. He is a true man of letters, which I am not, and I can only benefit from pondering his account.